Electric-arc lamp.



No. 677,605, 1 Patented July 2, IBM. T. SPENCER.

ELECTRIC ARC LAMP.

(Application filed Feb. 19, 1901.)

(No Model.)

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UNITED STATES PATENT @rmcn,

THOMAS SPENCER, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO HELIOS-UPTONCOMPANY, OF SAME PLACE.

ELECTRIC-ARC LAM P.

SPECIFICATION forming part of Letters Patent No. 677,605, dated July 2,1901.

Application filed Fehrnaryl 1901. Serial No. 47,987. (No 'model.)

To all whom it may concern:

Be it known that I, THOMAS SPENCER, of Philadelphia, in the State ofPennsylvania, have invented certain new and useful Improvements inElectric-Arc Lamps, whereof the following is a specification, referencebeing had to the accompanying drawings.

This invention relates particularly to electric-arc lamps adapted foroperation in an alternating-current circuit, and my improvements are ofspecial advantage in their application to lamps of the inclosed-arctype.

It is the object of my invention to provide means to regulate an arcwith greater accuracy than has been hitherto attainable in analternating-arc lamp and in view of the increased stability of the arcto permit such a lamp to be operated with a higher voltage at the arcthan has been hitherto possible in a circuit of given Voltage, thusreducing the shadow of the carbons and thereby increasing the availableamount of. light produced.

My invention consists in the employment of a transformer whose primarycoil is in series circuit with the regulating-coil of the lamp and whosesecondary coil is in series circuit with the lamp-arc, whereby the arcis supplied with the current induced in the secondary coil of saidtransformer, and the compensating adjustment of the length of the arc iseffected by the current through said primary coil before thefluctuations in the induced current in said secondary coil can bemanifested at the arc, so that each fluctuation in the current isneutralized and the arc remains stable.

It is well known that an arc cannot be burned in direct connection witha constantpotential circuit for the reason that the resistance of thearc decreases with any increase of current and increases with anydecrease of current,-producin g violent fluctuations of the are. As theresistance at the arc may be increased by lengthening the are it wouldseem theoretically possible to compensate for variations in the currentby variations in the distance of separation of the carbons. However, asthe force to separate the carbons is derived from the current and theconsiderable inertia of the regulating mechanism must be overcome beforeany movement thereof can be effected the compensating adjustment of thelength of the are, initiated by a given fluctuation in the current, isalways so much delayed that the fluctuation is manifested at I the arein advance of the adjustment. Therefore the regulating mechanismaforesaid is usually supplemented by a choking coil or by a deadresistance, both of these devices havin g characteristics opposite tothat of the arc, to wit: The drop of electrical potential across themincreases when the current increases and decreases when the currentdecreases.

Although the ordinary method of regulation aforesaid produces stabilityin the are, it requires so much self-induction or resistance that it isimpossible to operate a lamp with that length of are which will give thegreatest amount of light per unit of energy consumed.

In the accompanying drawings, Figure 1 shows a convenient embodiment ofmy inven tion, and Fig.2 is a diagram illustrating the peculiarvariations in the current which it is the object of this invention tocompensate.

Referring to Fig. 1, 1 1 are the terminals of the lamp-circuit, whichincludes the movable carbon 2 and the stationary carbon 3, between which-the are 4 is formed. The transformer 5 comprises the primary coil 6, inseries circuit with the regulating-coil 7, and the secondary coil 8, inseries circuit with the are 4:.

Said regulating-coil 7 is arranged to operate on the plunger 9, attachedto the carbonholder 10, which latter carries at its lower extremity thering-clutch 11 for the carbon 2 and is provided at its upper extremitywith the head 12, which cooperates with the cylinder 13 to form adash-pot serving to check the movement of said plunger 9.

The choking-coil 14: is in series circuit with the primary coil 6 of thetransformer and is in the secondary coil of the transformer, thepeculiar operation of my invention may be understood by reference to theconventional diagram, Fig. 2, wherein the waves in the line 18,rising'above and falling below the zero-line 19,1'espeetively,indicatethe momentary maximum potential of the current at each alternationthereof. In such a representation of a uniform current the waves in theline 18 would be of equal amplitude, and the difference in amplitude ofthe waves (shown in Fig. 2) indicates the fluctuations in the currentwhich it is the object of my invention to compensate. The full lines 20,touching the crests of the waves in the line 18, indicate the phases ina current fluctuation in the primary coil. 6 of the transformer 5, andthe dotted lines 21indieate the phases of the corresponding fluctuationin the current induced in the secondary coil 8 of the transformer 5,which latter fluctuation induced in the arc-circuitlags so farbehind theinitial fluctuation in the primary regulatingcircuit as to permit theregulatingcoil 7 to overcome the inertia of the regulating mechanism andmake the necessary adjustment of the length of the are before thedelayed fluctuation in the secondary circuit can be manifested at thearc. Therefore the length of the are in my improved lampbeingautomatically varied in precise accordance with each fluctuation ofthe current supplied thereto and in such sequence that the stability ofthe arc is constantly maintained, the lamp may be operated with avoltage at the are very nearly equal to that of the supply-circuit, withall of the advantages of efficiency and economy incident to such acondition of op eratiou.

I do not desire to limit myself to the precise construction orarrangement of myimprovements herein set forth, as it is obvious thatvarious modifications may be made therein without departing from theessential features of my invention.

I claim 1. The combination with an electricarc lamp; of a transformerwhose primary coil is in series circuit with the regulating-coil of thelamp, and whose secondary coil is in series circuit with the lamp-arc;whereby compensatingadj ustment of the length of the are is offected bya fluctuation of the current through the primary coil of the transformerbefore the corresponding fluctuation in the current induced in thesecondary coil is manifested at the are.

2. The combination with an electric-arc lamp; of a transformer Whoseprimary coil is in series circuit with the regulating-coil of the lamp,and whose secondary coil is in series circuit with the lamp-arc; and aself-induction in series with the primary coil of said transformer andsaid regulating-coil; whereby compensatingadjustment of the length ofthe arc is effected by a fluctuation of the current through the primarycoil of the transformer before the corresponding fluctuation in thecurrent induced in the secondary coil is manifested at the are.

3. The combination with an electric-arc lamp; of a transformer whoseprimary coil is in series circuit with the regulating-coil of the lamp,and whose secondary coil is in se ries circuit with the lamp-arc; achoking-coil in series with the primary coil of said transformer andsaid regulating-coil; and means to adjust-ably vary the effectiveself-induction of said choking-coil; whereby compensating adjustment ofthe length of the arc is effected by a fluctuation of the currentthrough the primary coil of the transformer before the correspondingfluctuation in the current induced in the secondary coil is manifestedat the are.

4. In an clectricarc lamp comprising opposed carbous, the combinationwith a regulating-coil arranged to separate said carbons; of the primarycoil of a transformer in series circuit with said regulating-coil; andthe sec ondary coil of said transformer in series circuit with the arebetween said carbons, substantially as set forth.

5. In an electric-arc lamp comprising opposed carbons, the combinationwith a plungcr operative to separate said carbons; of a regulating-coilarranged to actuate said plunger, the primary coil of a transformer inseries circuit with said regulating-coil; and the secondary coil of saidtransformer in series circuit with the are between said carbons,substantially as set forth.

6. In an electric-arc lamp comprising opposed carbons, the combinationwith a plunger operative to separate said carbons; of a regulating-coilarranged to actuate said plunger; the primary coil of a transformer inseries circuit with said regulating-coil; the secondary coil of saidtransformer in series circuit with the are between said carbons; and avariable resistance in series circuit with saidregulating-coil,substantially as set forth.

In testimony whereof I have hereunto signed my name, at Philadelphia,Pennsylvania, this 11th day of February, 1901.

THOMAS SPENCER.

Vitnesses:

FRANK S. MARI-1, HARRY HUSKEY.

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